Features and Main Uses of High Strength Bolts for Special Screws

　　Special ScrewsCharacteristics and main uses of high-strength bolts

Special grade screws have high strength and performance of bolts, so the scope of application is also relatively wide, mainly used for steel structure engineering connection fastening. The main feature of high-strength bolts is limited to one-time use, generally used for permanent connection, not repeated use.

High-strength bolts of super-grade screws are mainly used to connect steel structural plates in steel structure engineering. High-strength bolts are divided into torsional shear high-strength bolts and large hexagonal high-strength bolts. Large hexagonal high-strength bolts are due to the high strength of ordinary screws, while torsional shear high-strength bolts are improvements to large hexagonal high-strength bolts for better construction.

The construction of high-strength bolts must be tightened first and then tightened. The high-strength bolts of special screws need to use impact electric wrenches or torque adjustable electric wrenches. However, there are strict requirements for the final fastening of high-strength bolts. Torsional shear electric wrench must be used for the final fastening of high-strength bolts, and torsional shear electric wrench must be used for the final fastening of high-strength bolts.

Make sure that the load and wedge load do not meet the standard. Ensuring load and wedge load are key items for checking the mechanical properties of goods under tensile load (Class A), especially for high-strength fasteners. Ensure that the load is to check the plastic deformation resistance of the goods under regular tensile load. If the object does not meet the requirements, plastic deformation may occur due to the action of pre-tightening force and operating load, and then reduce the pre-tightening force to loosen the connection. The wedge load test is to check the tensile strength of the bolt and the joint strength of the head rod. This goal is not qualified. When the operating load is large, especially when the impact load or the supporting surface is partially loaded, cracking or turning will occur, resulting in joint failure and even safety accidents.

High-strength bolt decarburized layer interference of super-grade screws. Decarburization layer is also a project, because decarburization, so that the appearance of the hardness and strength of the parts greatly reduced, seriously affecting the appearance of the fastener contact strength and fatigue life, especially the thread part of the harm is more prominent. The main causes of decarburization are raw material decarburization, data reconstruction process and commodity heat treatment process. Hardness is unqualified, hardness and inspection are given priority. For fasteners, mechanical functions, the information of the functional level of commodity selection is different. When fasteners and mechanical functions are the basis of the first level, the workload and torque are determined according to the function and use level of the equipment. For a specific data, the hardness should be controlled at a reasonable level. High hardness may reduce the anti-fatigue function of the commodity, some companies in order to improve the strength of the goods, the hardness control at a higher level to form a number of commodity overruns.